Example 3: Displaying Alarms when a Temperature Signal Meets a Specified Value

The following procedure describes how to display an alarm when a temperature signal you are logging exceeds a temperature you specify. This example uses the project you created in Example 1: Logging a Temperature Signal and modified in Example 2: Logging a Temperature Signal with Start and Stop Conditions.

Complete the following steps to configure LabVIEW SignalExpress to display an alarm when the temperature signal rises above 85 degrees Fahrenheit.

1. Open the project you saved in Example 2: Logging a Temperature Signal with Start and Stop Conditions.
2. Select View»Recording Options to display the Recording Options tab.
3. In the Category list, select Alarms to display the Alarms page.
4. Click the Add button to add a new alarm to the Alarm list and display additional configuration options.
5. Verify that Thermocouple - Dev1_ai0 appears in the Signal pull-down menu and Above appears in the Condition pull-down menu.
6. Enter 85 in the Value field to specify that LabVIEW SignalExpress displays an alarm when the signal from the thermocouple rises above 85 degrees Fahrenheit.
7. Switch to the Data View tab and click the Run button to run the project continuously. The status indicator below the Project View displays Waiting for start conditions until LabVIEW SignalExpress detects the start condition you configured in Example 2: Logging a Temperature Signal with Start and Stop Conditions.
8. After the start condition is met, the status indicator updates to display Recording. If the logged signal does not appear on the Data View tab, drag the signal from the Logged Data window to the Data View tab to view the progress of the log.
9. When the temperature signal exceeds 85 degrees Fahrenheit, a red alarm indicator appears on the graph of the log. The alarm remains active until the temperature falls below 85 degrees.
10. The project runs and LabVIEW SignalExpress logs the signal until the stop condition is met. After the stop condition is met, expand the log in the Logged Data window, right-click Thermocouple, and select Show Alarms and Events from the shortcut menu to display a dialog box that list the alarms and events that occurred during the logging operation. You can click the Export button on this dialog box to save the list to a text file.
11. Click the OK button to close the dialog box and select File»Save Project to save the project.

This example and the two that precede it describe different ways to configure logging operations. After a logging operation is complete, you can use LabVIEW SignalExpress to view and analyze the logged signal. Example 4: Analyzing a Logged Temperature Signal describes how to analyze the logged temperature signal in LabVIEW SignalExpress.